In lithography techniques, for example, a resist film composed of a resist material is formed on a substrate, and the resist film is subjected to selective exposure of radial rays such as light or electron beam through a mask having a predetermined pattern, followed by development, thereby forming a resist pattern having a predetermined shape on the resist film.
A resist material in which the exposed portions become soluble in a developing solution is called a positive-type, and a resist material in which the exposed portions become insoluble in a developing solution is called a negative-type.
In recent years, in the production of semiconductor elements and liquid crystal display elements, advances in lithography techniques have led to rapid progress in the field of pattern miniaturization.
Typically, these miniaturization techniques involve shortening the wavelength (increasing the energy) of the exposure light source. Conventionally, ultraviolet radiation typified by g-line and i-line radiation has been used, but nowadays KrF excimer lasers and ArF excimer lasers are starting to be introduced in mass production. Furthermore, research is also being conducted into lithography techniques that use an exposure light source having a wavelength shorter (energy higher) than these excimer lasers, such as electron beam, extreme ultraviolet radiation (EUV), and X ray.
With respect to a contact hole pattern formed on a resist film, the shape tend to largely vary such as connection of the holes, as the hole diameter and the pitch becomes smaller. As a method of recovering connected holes and dividing into each hole, a method has been proposed in which a block copolymer is applied to a resist film having a contact hole pattern formed thereon, and a phase-separation structure having a cylinder structure is formed inside the connected holes, followed by selectively removing a phase constituting the center of the cylinder structure, thereby forming a contact hole having a relatively uniform hole diameter than the first contact hole pattern (see, for example, Patent Documents 1 and 2).